1. Field of Invention
The invention generally relates to the field of medical surgical instruments, specifically structures for supporting one or more diagnostic or therapeutic elements in contact with body tissue. In a more particular sense, the invention relates to structures well suited for supporting one or more electrode elements within the heart.
2. Description of the Related Art
There are many instances where diagnostic and therapeutic elements must be inserted into the body. One instance involves the treatment of cardiac conditions such as atrial fibrillation and atrial flutter which lead to an unpleasant, irregular heart beat, called arrhythmia. The treatment of cardiac arrhythmia requires electrodes capable of creating tissue lesions having a diversity of different geometries and characteristics, depending upon the particular physiology of the arrhythmia to be treated.
For example, it is believed that the treatment of atrial fibrillation and flutter requires the formation of continuous lesions of different lengths and curvilinear shapes in heart tissue. These lesion patterns require the deployment within the heart of flexible ablating elements having multiple ablating regions. The formation of these lesions by ablation can provide the same therapeutic benefits that the complex incision patterns that the surgical maze procedure presently provides, but without invasive, open heart surgery.
The task is made more difficult because heart chambers vary in size from individual to individual. They also vary according to the condition of the patient. One common effect of heart disease is the enlargement of the heart chambers. For example, in a heart experiencing atrial fibrillation, the size of the atrium can be up to three times that of a normal atrium.
A need exists for electrode support structures that can create lesions of different geometries and characteristics, and which can readily adopt to different contours and geometries within a body region, e.g., the heart.
The invention provides structures for supporting operative therapeutic or diagnostic elements within an interior body region, like the heart. The structures possess the requisite flexibility and maneuverability permitting safe and easy introduction into the body region. Once deployed in the body region, the structures possess the capability to exert force against tissue thereby deforming the tissue resulting in conformance between tissue and elements.
A probe assembly in accordance with one embodiment of the invention includes an outer member including a wall defining an interior bore having a distal end and a proximal end, and an elongate body, defining a distal end, a proximal end and an exterior, carried within the outer member. The distal end of the elongate body includes at least one operative element. The elongate body further includes a flexible spline extending from adjacent the distal end toward the proximal end which has a first stiffness. The assembly also includes a control element defining a distal portion extending into the distal end of the elongate body and operably connected to the flexible spline, and a proximal portion extending along the exterior of the elongate body within the outer member toward the proximal end of the outer member. At least the portion of the control element aligned with the distal end of the elongate body has a second stiffness which is less than the first stiffness.
There are many advantages associated with this embodiment of the present invention. For example, this embodiment is more compact than conventional probes. Additionally, the relatively flexible control element is less likely to cause tissue damage than the control elements in conventional probes.
An assembly in accordance with another embodiment of the present invention includes an elongate catheter body, and a control element defining a distal portion operably connected to the distal portion of the catheter body and a proximal portion associated with, and extending along, the exterior surface of the catheter body to an area adjacent the proximal end of the catheter body. The assembly also includes an apparatus, associated with the catheter body and the control element, that is adapted to secure the control element in predetermined relation to the catheter body.
There are many advantages associated with this embodiment of the present invention. For example, the control element, which is typically a pull wire, is less likely to wrap around the catheter body than is the control element in a conventional device. As a result, when the present assembly is used in conjunction with a sheath, the catheter is less likely to become stuck within the sheath.
A probe assembly in accordance with another embodiment of the invention includes an outer member including a wall defining an interior bore, and an elongate body carried within the outer member. The distal portion of the elongate body includes at least one operative element. The elongate body also includes a flexible spline extending from adjacent the distal end toward the proximal end. The flexible spline defines a first cross-sectional shape over a substantial portion thereof and a second cross-sectional shape over a relatively small portion thereof. The assembly also includes a control element defining a distal portion operably connected to at least one of the distal end and distal portion of the elongate body, and a proximal portion extending along the exterior of the elongate body within the outer member toward the proximal end of the outer member.
There are many advantages associated with this embodiment of the present invention. For example, the second cross-sectional shape may be a relatively flat shape. As compared to conventional probe assemblies, the flat shape provides increased predictability and consistency in the deflection direction of the elongate body and, therefore, better control of the movement of the elongate body. This is especially true when the elongate body is used to form loops.